Kernel memory corruption via encap-entry race
Published May 21, 2024 · Updated Aug 5, 2026
Use-after-free in Linux kernel mlx5e code allows local users to corrupt kernel memory through concurrent encapsulation-entry updates. mlx5e_rep_neigh_update iterates an encapsulation list while TC filter changes can delete an entry, then mlx5e_encap_take reads the freed object. Exploitation requires mlx5 encapsulation offload and precise concurrent neighbor and filter activity; the observed result is a KASAN-detected kernel memory fault that can crash the host.
Summary
What happened
Use-after-free in Linux kernel mlx5e code allows local users to corrupt kernel memory through concurrent encapsulation-entry updates. mlx5e_rep_neigh_update iterates an encapsulation list while TC filter changes can delete an entry, then mlx5e_encap_take reads the freed object. Exploitation requires mlx5 encapsulation offload and precise concurrent neighbor and filter activity; the observed result is a KASAN-detected kernel memory fault that can crash the host.
The record
- CVE
- CVE-2021-47247
- Published
- May 21, 2024
- Updated
- Aug 5, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- CWE-416, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- May 21, 2024CVE publishedPublication date reported by the CVE source.
- Aug 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=2a1f1768fa17805ca2e937e2e034a7c3433d3bdc <0d1e7a7964ce6abb28883a3906bbc20fe0009f03
- Affected versionversion=2a1f1768fa17805ca2e937e2e034a7c3433d3bdc <b6447b72aca571632e71bb73a797118d5ce46a93
- Affected versionversion=2a1f1768fa17805ca2e937e2e034a7c3433d3bdc <fb1a3132ee1ac968316e45d21a48703a6db0b6c3
- Affected versionversion=5.4
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Public exploit references
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Technologies
Your stack
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Your stack
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